Polycarbonate or thermoplastic panels used in climbing walls and the likes may experience cracking. A climbing panel, while extremely strong and durable, may be subject to radial stress cracks specifically located around the edge of a hole pre-drilled in the panel, which is used to affix a climbing hold to the panel of the climbing structure.
The current method of attaching climbing holds to polycarbonate or thermoplastic sheet that form the panels of a climbing surface is to use a combination of a bolt, flat and locking washers, and either a nut, an embedded nut (‘T’ Nut) or a threaded insert. When attaching the climbing hold the assembler needs to exert sufficient torque on the bolt creating compressive forces between the climbing hold and the panel in order to prevent the climbing hold from spinning. The majority of compressive forces exerted on the panel, using the current method, are located immediately around the edges of the pre-drilled hole in the panel and this dramatically increases the possibility of the panel cracking or fracturing in a Tangential/Radial direction away from the hole. Coupled with the live load exerted on the climbing hold by a climber, these radial cracks or fractures have the potential to extend and creep into a full crack, not dissimilar to that of a cracked windshield.
Such radial cracks or fractures may not be immediately detectable, particularly if the climbing hold or the hardware used to affix a climbing hold to the panel obscures them. They are, nonetheless, serious in that the integrity of the panel is compromised, potentially worsens over time with live stress loads, and cannot be repaired.